Insulating jackets thermally protect kidneys in an ex vivo model of second warm ischemia.

BACKGROUND: Kidney transplantation is the current optimal treatment for suitable patients with end-stage renal disease. The second warm ischemic time (SWIT) is known to negatively impact delayed graft function, and long-term graft survival, and methods are required to ameliorate the impacts of SWIT on transplantation outcomes. MATERIALS AND METHODS: This study primarily focused on determining the effect of a novel thermally insulating jacket on the thermal profile of the human kidney and quantifying the reduction in thermal energy experienced using this device (KPJ™). An ex vivo simulated transplantation model was developed to determine the thermal profiles of non-utilized human kidneys with and without KPJ™ (n = 5). Control kidney temperature profiles were validated against the temperature profiles of n = 10 kidneys during clinical kidney transplantation. RESULTS: Using the ex-vivo water bath model, the thermally insulated human kidney reached the 15°C metabolic threshold temperature at 44.5 ± 1.9 min (vs control: 17.3 ± 1.8 min (p = 0.00172)) and remained within the 18°C threshold until 53.3 ± 1.3 min (vs control: 20.9 ± 2.0 min (p = 0.002)). The specific heat capacity of KPJ™ protected kidney was four-fold compared to the control kidney. The clinical temperature audit, closely correlated with the water bath model, hence validating this ex-vivo human kidney transplant model. CONCLUSION: Intraoperative thermal protection is a simple and viable method of reducing the thermal injury that occurs during the SWIT and increasing the specific heat capacity of the system. Such technology could easily be translated into clinical kidney transplant practice.

Protection From the Second Warm Ischemic Injury in Kidney Transplantation Using an Ex Vivo Porcine Model and Thermally Insulating Jackets.

BACKGROUND: Kidney transplantation is the optimum treatment for kidney failure in carefully selected patients. Technical surgical complications and second warm ischemic time (SWIT) increase the risk of delayed graft function (DGF) and subsequent short- and long-term graft outcomes including the need for post-transplant dialysis and graft failure. Intraoperative organ thermal regulation could reduce SWIT, minimizing surgical complications due to time pressure, and limiting graft ischemia-reperfusion injury. METHODS: A novel ischemic-injury thermal protection jacket (iiPJ) was designed and fabricated in silicone composite and polyurethane (PU) elastomer prototypes. Both were compared with no thermal insulation as controls. Time to reach ischemic threshold (15°C) and thermal energy transfer were compared. A water bath model was used to examine the thermal protective properties of porcine kidneys, as a feasibility study prior to in vivo translation. RESULTS: In both iterations of the iiPJ, the time taken to reach the warm ischemia threshold was 35.2 ± 1.4 minutes (silicone) and 38.4 ± 3.1 minutes (PU), compared with 17.2 ± 1.5 minutes for controls (n = 5, P < .001 for both comparisons). Thermal energy transfer was also found to be significantly less for both iiPJ variants compared with controls. There was no significant difference between the thermal performance of the 2 iiPJ variants. CONCLUSION: Protection from SWIT by using a protective insulation jacket is feasible. With clinical translation, this novel strategy could facilitate more optimal surgical performance and reduce transplanted organ ischemia-reperfusion injury, in particular the SWIT, potentially affecting delayed graft function and long-term outcomes.

Clinical evaluation of rapid 3D print-formed implants for surgical reconstruction of large cranial defects.

BACKGROUND: To clinically evaluate 3D print-formed implant process, using cranioplasty as a proof of concept, to examine its effectiveness and utility as a method of intraoperative implant fabrication. METHODS: Twelve patients had a 3D print-formed template created for patient-specific implant manufacture. Of these patients, 10 received intraoperatively formed polymethylmethacrylate cranioplasty implants between 2013 and 2019. The 3D print-formed implant templates produced to manufacture these patient-specific implants were generated using patient computed tomography scans and 3D printed using fused deposition modelling technology. Cosmetic and functional results were determined by participating surgeons, in conjunction with a patient questionnaire. RESULTS: The functional results and stability of the implants were deemed to be favourable by participating surgeons. Three of the 10 patients completed a post-cranioplasty survey, all of whom judged their cosmetic results as good or excellent. At time of writing, the rate of surgical revision was zero and without clinically adverse outcomes. CONCLUSIONS: 3D print-formed implants are an effective method of patient-specific implant formation.